Our overall study hypothesis is that arterial stiffness plays an increasingly important role in the relationship between high blood pressure (BP) and lowered cognitive performance with advancing age and is an independent risk factor for lowered cognitive performance. Aortic pulse wave velocity (aPWV) and related measures (Augmentation Index) are reliable and valid indices of arterial stiffness. We propose to call back 900 individuals participating in longitudinal studies of brachial BP and cognitive performance for a new study relating arterial stiffness to cognitive performance. We will also introduce new central aortic and carotid BP measures and relate them to cognitive functioning. All of the current investigations relating BP to cognitive performance have employed the traditional pressure-cuff method of assessing BP at the brachial artery (a peripheral BP assessment). We will introduce applanation tonometry technology. This will allow us to examine relations between aPWV and cognitive functioning, as well as "closer to the brain" arterial (aortic and carotid) BP estimates and cognitive functioning. Among our major hypotheses are: (1) aPWV will be an independent predictor of cognitive performance; (2) aPWV will exhibit a greater magnitude of association with cognitive performance for older than for younger persons; (3) magnitude of associations between the site-specific BP variables and cognitive functioning will be ordered as follows, highest to lowest, carotid BP> aortic BP> brachial BP; (4) greater differences among these pressures will be observed for systolic than diastolic pressure and for younger than older adults. The hypothesized relations will hold despite statistical adjustment for variables which confound relations between BP and cognitive performance and may confound relations between aPWV and cognitive performance. As an ancillary benefit of these new studies, we will continue a 29-year longitudinal study relating brachial artery BP to cognitive performance, thus allowing us to examine both linear and non-linear relations between brachial BP and changes in performance with age.